function_benchmarker 0.1.2

A proc macro for benchmarking Rust code
Documentation 
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use proc_macro::TokenStream;
use quote::quote;
use syn::parse_macro_input;

#[proc_macro_attribute]
pub fn benchmark(_attrs: TokenStream, item: TokenStream) -> TokenStream {
    let input_fn = parse_macro_input!(item as syn::ItemFn);

    let fn_name = &input_fn.sig.ident;
    let fn_block = &input_fn.block;
    let func_return = &input_fn.sig.output;
    let func_args = &input_fn.sig.inputs;

    let expanded = quote! {
        fn #fn_name(#func_args) #func_return {
            use jemalloc_ctl::{epoch, stats::allocated};
            println!("Entering function: {}", stringify!(#fn_name));
            let e = epoch::mib().unwrap();
            let allocated_before = allocated::mib().unwrap();
            e.advance().unwrap();
            let memory_before = allocated_before.read().unwrap();
            let start = std::time::Instant::now();
            let result = (|| #fn_block)();
            let duration = start.elapsed().as_millis();
            e.advance().unwrap();
            let memory_after = allocated_before.read().unwrap();
            let memory_used = memory_after - memory_before;
            println!("Exiting function: {} (took {} ms) memory used: {:?} bytes", stringify!(#fn_name), duration, memory_used);
            result
        }
    };

    TokenStream::from(expanded)
}